With the development of the Chinese steel industry, the production volume, the quality and the variety of heavy or thick plate production have improved dramatically and more efforts are being put into further research with in-depth studies. TMCP (Thermo Mechanical Controlling Process) has been studied for many years and has proved to be an important method for improving the properties of steel plate products. When it comes to traditional heavy plate rolling, because of the low penetration of deformation, the defects of the core region are difficult to eliminate, there are many flaws and problems such as double bulging and edge overlap, the yield is low, the temperature cannot be properly controlled, the homogeneity of microstructure and structure is poor, especially in the thickness-direction, and productivity is low due to the long intermediate holding time for the intermediate slab.
The intermediate cooling process is a fast cooling process which controls the temperature of the intermediate slab between the rough rolling and the finish rolling. It has been applied to industrial production of heavy or thick plate for its ability to reduce holding time of the intermediate slab, increasing productivity, improving surface quality, and effectively suppressing austenite grain from coarsening.
Currently, laminar cooling equipment, which is arranged far away from the rolling mill, is generally used in the intermediate cooling process; it's very difficult to achieve a large temperature gradient in the thickness direction during rolling and precise control of plate temperature.
In general, ultra heavy plate is prone to the defect of lamellar tearing and poor property in the thickness direction (the Z direction). This is mainly because of segregation, holes, porosity, micro-cracks, poor homogeneity in the thickness direction or coarse grains existing in the center. Currently, there is no good solution for this problem.